Abstract
The semi-domesticated reindeer is a northern species of Cervidae
that is exposed to extreme seasonal changes in temperature and nutrition
in its living environment. The objective of this study was to examine
the significance of thermogenic brown adipose tissue (BAT) for the
survival of newborn reindeer in the cold during the critical perinatal
period. The other main objective was to study the effect of wintertime
undernutrition on serum and bone marrow fatty acid composition in
yearling reindeer, with particular attention on the proportions
of unsaturated and polyunsaturated fatty acids (PUFAs) and their
feasibility as indicators of nutritional status.
The results showed that the most of the adipose tissues in
newborn reindeer were functionally active BAT. The tissue had specific
anatomical locations, specialized cell morphological structure, high
aerobic capacity, and tissue-specific mitochondrial 32000 Mr-uncoupling
protein (UCP1) that is considered a rate-limiting
factor for thermogenesis. The most readily mobilized fatty acids
from BAT triacylglycerols were arachidonic, linoleic, and α-linolenic
acids. BAT was most active at birth and during the close perinatal
period but its aerobic capacity declined during the first month
of life while UCP1 disappeared and the tissue
gradually adopted the histological characteristics of white adipose tissue.
The newborn reindeer had very low proportions of the principal
C18-PUFAs, linoleic and α-linolenic acids, in serum lipids.
However, the proportions of C18-PUFAs increased during the first few
days of life by a rate that suggests a selective retention of these
fatty acids from milk lipids. A prolonged restricted feeding of
reindeer with lichen during winter and spring induced significant reductions
in the proportions of linoleic and α-linolenic acids in
serum cholesteryl esters and phospholipids, while proportion of
arachidonic acid and serum prostaglandin PGF2α metabolite concentration
increased. Plasma leptin and insulin levels decreased in parallel
with decreases in feed intake and body weight. In freely ranging
reindeer, the proportions of oleic acid and principal C18-PUFAs
were significantly reduced in femur bone marrow triacylglycerols
as a result of a wintertime undernutrition.
In conclusion, active BAT is the dominant adipose tissue type
in the newborn reindeer and it is likely to have a major significance
on the thermoregulatory heat production and cold resistance of reindeer
during the perinatal period. The changes in the specific PUFA proportions
of serum and bone marrow lipids refleict the changes in the nutritional
status and suggest that these fatty acids are preferentially utilized
during prolonged wintertime undernutrition.
| Identifer | oai:union.ndltd.org:oulo.fi/oai:oulu.fi:isbn951-42-5689-1 |
| Date | 30 May 2000 |
| Creators | Soppela, P. (Päivi) |
| Publisher | University of Oulu |
| Source Sets | University of Oulu |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/doctoralThesis, info:eu-repo/semantics/publishedVersion |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess, © University of Oulu, 2000 |
| Relation | info:eu-repo/semantics/altIdentifier/pissn/0355-3191, info:eu-repo/semantics/altIdentifier/eissn/1796-220X |
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